EP3671365A1 - Timepiece dial - Google Patents

Abstract

The invention relates to a dial (1) comprising a support (2), a mother-of-pearl sheet (4) having an obverse and a cuff and covering at least partially the support (2), and at least one decorative element ( 6) provided on the reverse side of said mother-of-pearl sheet (4), said decorative element (6) being arranged to be visible on the obverse of the mother-of-pearl sheet (4) under the effect of a stimulus and invisible on the obverse of the mother-of-pearl sheet (4) in the absence of said stimulus, said decorative element (6) defining around it, on the reverse of the mother-of-pearl sheet (4), at least one first empty zone (10 ), and at least one second empty zone (12) on the obverse of the mother-of-pearl sheet (4), facing said first empty zone (10). Said dial (1) comprises at least one color compensation layer (14) deposited on at least one of the first empty zone (10) and second empty zone (12), the color of said color compensation layer (14 ) being chosen so that the color difference ΔE in the CIE Lab color space between the color compensation layer and the decoration element in the absence of said stimulus, perceived by a user looking at the obverse of the sheet of mother-of-pearl is less than 3. The present invention also relates to a timepiece comprising such a dial.

Description

Field of the invention

The invention relates to a dial comprising a support, a mother-of-pearl sheet having an obverse and a cuff and covering at least partially the support, and at least one decorative element provided on the reverse side, said decorative element being arranged to be visible on the obverse of the mother-of-pearl leaf under the effect of a stimulus and invisible on the obverse of the mother-of-pearl leaf in the absence of said stimulus, said decorative element defining around it, on the reverse of the mother-of-pearl sheet, at least a first empty zone and at least a second empty zone on the obverse of the mother-of-pearl sheet, opposite the first empty zone. The present invention also relates to a timepiece comprising such a dial.

Invention background

The use of mother-of-pearl for the manufacture of dials is already known in the watchmaking field for its particular aesthetics. The mother-of-pearl has a biological origin, iridescent reflections and a translucency which make each piece of mother-of-pearl unique. Depending on its origin, the mother-of-pearl can have various intrinsic colors (eg white, gray, pink, green). In order to modify its aesthetics, the mother-of-pearl can be colored by soaking in a dye bath. A decoration can also be applied on the obverse (visible side by a user of the timepiece) or the reverse (back side, turned towards the inside of the timepiece) of the mother-of-pearl, the latter option based on the translucency properties of the material. The visible decoration can be formed of a colored lacquer or a metallic deposit. The lacquer can be applied by techniques usually used for lacquering such as spraying, pad printing or screen printing. A metallic deposit can also be applied by physical vapor deposition techniques such as PVD. Other inorganic layers, such as for example nitrides, carbides or oxides, can be applied by PVD or CVD.

Depending on its thickness on the obverse of the coin, the decor can even cover and hide the particular morphology of the mother-of-pearl. In these techniques, the decoration, even placed behind the mother-of-pearl dial, is always visible on the final piece.

The patent EP 1672436 mentions for example the manufacture of a mother-of-pearl dial of uniform metallic appearance by deposition of a metallic coating on the entire surface of the obverse of the dial.

The patent CH 559 924 describes a dial comprising a mother-of-pearl sheet under which elements of luminescent material are provided, visible at night and invisible by day so as not to be detected by the eye through the mother-of-pearl sheet. In this document, the luminescent material is applied uniformly on the reverse of the coin and does not allow a complex decoration to appear on the obverse of the mother-of-pearl.

The patent CH 697 210 describes a dial comprising a mother-of-pearl sheet, the rear face of which comprises cavities filled with phosphorescent pigments which make it possible to make visible under the mother-of-pearl a decoration visible in the dark, whose design and light intensity can be chosen according to the shape and depth of the cavities. However, the light intensity of the decoration in the dark must be limited in order to be able to guarantee the invisible nature of the phosphorescent pigments on the obverse of the coin when the dial is exposed to daylight.

Summary of the invention

The purpose of the present invention is to remedy these drawbacks by proposing a mother-of-pearl timepiece dial, comprising a decoration on the reverse of the piece and the decoration of which does not become visible on the obverse of the piece only under the effect of an external or internal stimulus, light, electric, or physical, for which the invisible character of said decoration on the obverse of the piece, when it is not under the effect of stimulus, has been improved.

The present invention also aims to provide a mother-of-pearl timepiece dial comprising several decorations on the reverse of the piece, visible on the obverse of the piece with different light intensities when they are under the effect of their stimulus, all the decorations being invisible on the obverse of the coin when they are not under the effect of their stimulus.

To this end, the invention relates to a dial comprising a support, a mother-of-pearl sheet having an obverse and a cuff and covering at least partially the support, and at least one decorative element provided on the reverse side of said mother-of-pearl sheet. , said decorative element being arranged to be visible on the obverse of the mother-of-pearl sheet under the effect of a stimulus and invisible on the obverse of the mother-of-pearl sheet in the absence of said stimulus, said decorative element defining around it, on the reverse of the mother-of-pearl sheet, at least a first empty zone and at least a second empty zone on the obverse of the mother-of-pearl sheet, opposite the first empty zone.

According to the invention, the dial comprises at least one color compensation layer deposited on at least one of the first and second empty areas, the color of said color compensation layer being chosen so that the color difference ΔE in the CIE Lab color space between the color of the color compensation layer and the color of the decor element in the absence of said stimulus, perceived by a user looking at the obverse of the mother-of-pearl sheet, is less than 3 , preferably less than or equal to 1.

Thus, thanks to the color compensation layer, the invisible nature of the decoration on the obverse of the coin, when it is not under the effect of its stimulus, is improved. It is then possible to use a setting of greater luminous intensity when it is under the effect of its stimulus, or several decorations giving different light intensities, some of which may be high, without the risk of seeing them appear on the obverse of the coin when the stimulus is not applied.

The present invention also relates to a timepiece comprising such a dial.

Brief description of the drawings

• les figures 1 à 3 sont des vues schématisées de différents modes de réalisation d'un cadran selon la présente invention.

Other characteristics and advantages of the invention will appear more clearly on reading the following description of different embodiments of the invention, given by way of simple illustrative and nonlimiting examples, and of the appended figures, among which:

• the Figures 1 to 3 are schematic views of different embodiments of a dial according to the present invention.

Detailed description of preferred embodiments

The present invention relates to a timepiece dial, comprising a support, a mother-of-pearl sheet having an obverse and a lapel and covering at least partially the support, and at least one decorative element provided on the reverse side, between the support and the mother-of-pearl leaf.

The support is preferably metallic. It can be made of brass, based on gold, yellow or white, or silver, or any other suitable metal. It can be assembled with the mother-of-pearl sheet carrying the decorative element by plating, gluing or any other suitable means.

The decorative element is arranged to be visible on the obverse of the mother-of-pearl sheet under the effect of a stimulus and invisible on the obverse of the mother-of-pearl sheet in the absence of said stimulus.

The decorative element defines around it, on the reverse of the mother-of-pearl sheet, at least a first empty zone, that is to say an area of the reverse of the mother-of-pearl not occupied by said decorative element. The decorative element also defines, by projection on the obverse of the mother-of-pearl sheet, opposite the first empty zone, at least a second empty zone, that is to say a zone on the obverse of the mother-of-pearl through which said decorative element, on the reverse side, does not appear.

According to the invention, the dial comprises at least one color compensation layer deposited on at least one of the first and second empty areas, the color of said color compensation layer being chosen so that the color difference ΔE in the CIE Lab color space between the colors of the color compensation layer and of the decoration element in the absence of said stimulus, perceived by a user looking at the obverse of the mother-of-pearl sheet, is less than 3, preferably less than or equal to 1.

$L_1^{*},$

$a_1^{*},$

$b_1^{*}$

sont les coordonnées dans l'espace colorimétrique CIE Lab de la première couleur à comparer et $L_2^{*},$

$a_2^{*},$

$b_2^{*}$

sont les coordonnées dans l'espace colorimétrique CIE Lab de la seconde couleur à comparer.The color difference ΔE in the CIE Lab color space is defined as a difference measurement between two colors by equation (I): $$\mathrm{\Delta }\mathit{E}*=\sqrt{{\left({\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="imgf0001.png"\; state="\{\{state\}\}">L</figure-callout>}}_2^{*}-{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="imgf0001.png"\; state="\{\{state\}\}">L</figure-callout>}}_1^{*}\right)}^2+{\left({\mathrm{at}}_2^{*}-{\mathrm{at}}_1^{*}\right)}^2+{\left(b_2^{*}-b_1^{*}\right)}^2}$$

${\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="imgf0001.png"\; state="\{\{state\}\}">L</figure-callout>}}_1^{*},$

${\mathrm{at}}_1^{*},$

$b_1^{*}$

are the coordinates in the CIE Lab color space of the first color to compare and ${\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="imgf0001.png"\; state="\{\{state\}\}">L</figure-callout>}}_2^{*},$

${\mathrm{at}}_2^{*},$

$b_2^{*}$

are the coordinates in the CIE Lab color space of the second color to be compared.

The decorative element comprises stimulus-reactive particles, namely phosphorescent or photochromic particles to be sensitive to a light stimulus, electromromic particles to be sensitive to an electrical stimulus, or thermochromic particles to be sensitive to a variation of temperature.

Preferably, the decorative element is obtained from a lacquer or a reactive ink containing an epoxy or polyurethane binder, to which are added the reactive particles. The size of the reactive particles can be between 0.5 μm and 100 μm, and preferably between 10 μm and 50 μm. Inorganic or organic additives can be used to modify the shade of the reactive lacquer and achieve the desired color if necessary, its texture or its optical properties. The color of the lacquer or reactive ink is chosen so that the decorative element, when not under the effect of its stimulus, modifies the intrinsic appearance of the mother-of-pearl sheet as little as possible, and become completely invisible on the obverse of the dial using the color compensation layer.

The decorative element is provided between the support and the mother-of-pearl sheet. For this purpose, the decorative element can be formed on the reverse of the mother-of-pearl sheet, either directly on the surface of the reverse of the mother-of-pearl, or in at least one blind cavity formed from the reverse of the mother-of-pearl and arranged to receive said decorative element.

Advantageously, the reverse of the mother-of-pearl sheet may include several blind cavities in order to form several decorative elements.

Said blind cavities are formed from the reverse of the mother-of-pearl sheet by laser, mechanical or manual engraving in order to draw blind cavities whose geometries and depths are controlled as a function of the element of decoration to be represented and as a function of intensity of the decorative element which will appear through the mother-of-pearl leaf under the effect of its stimulus. The blind cavities are then selectively filled with reactive lacquer. The blind cavities allow a greater amount of reactive lacquer to be used, which increases the intensity of the optical phenomena. In addition, advantageously, the blind cavities have different depths in order to form several decorative elements which, under the effect of the stimulus, will appear with intensities which vary between the different decorative elements, creating color contrasts. .

The decorative element can also be placed on the support which will then be applied against the reverse of the mother-of-pearl, by plating or gluing for example.

Lacquer or reactive ink is applied selectively to create a decoration on the back of the mother-of-pearl sheet or support. The processes which can be implemented for this purpose are the lacquering or spraying of lacquer using a mask or a photosensitive lacquer to selectively deposit the lacquer, by selective ablation by laser or mechanical of the lacquer, serigraphy, pad printing or any other technique. appropriate printing.

The composition and the thickness of the color compensation layer used in the present invention are adapted as a function of the composition of the lacquer or of the reactive ink, of the thickness of the mother-of-pearl sheet and of its color, in order to obtain a compensation layer whose color makes it possible to satisfy equation (I).

The color compensation layer may be of an organic nature, such as a varnish comprising pigments or dyes making it possible to obtain the color necessary to satisfy equation (I).

The color compensation layer may be inorganic in nature, for example based on oxides or nitrides, for example zirconium or titanium or based on metals such as, for example, aluminum, silver or alloyed gold having the color necessary to satisfy equation (I).

Advantageously, the compensation layer is transparent, in particular when the compensation layer is applied to the obverse of the mother-of-pearl sheet.

In addition, the color compensation layer deposited on the first empty zone can also be metallic, intrinsically having the color necessary to satisfy equation (I).

The color compensation layer can be applied by spraying, dip coating, pad printing, screen printing, sol-gel, printing or by vacuum techniques such as PVD.

According to a variant of the invention, the surface of at least one of the first and second empty zones can be diffusive. The diffusive surface can be created on the reverse and / or obverse of the mother-of-pearl sheet by chemical, laser or mechanical engraving. Another variant is the use of a diffusive film applied to the surface of the mother-of-pearl, preferably on the obverse of the mother-of-pearl sheet.

According to a first embodiment of the invention shown in the figure 1 , the dial 1 comprises a support 2, a mother-of-pearl sheet 4 having an obverse and a reverse and several decorative elements 6 arranged directly on the reverse of the mother-of-pearl sheet 4 to form an image appearing through the obverse of the mother-of-pearl sheet 4 when the decor elements 6 are subjected to their stimulus. The mother-of-pearl sheet 4 and the decorative elements 6 are assembled on the support 2 by means of a layer of glue 8. The decorative elements 6 define around them, on the reverse of the mother-of-pearl sheet 4, the first empty zones 10, and, on the obverse of the mother-of-pearl sheet 4, opposite the first empty zones 10, second empty zones 12.

In this embodiment, the color compensation layer 14 according to the invention is provided on the reverse of the mother-of-pearl sheet 4 only on the first empty areas 10 around the decor elements 6. Thus, thanks to the compensation layer of color 14 according to the invention, a user 16 looking at the obverse of the mother-of-pearl sheet 4 does not perceive a difference in color between the color, through the mother-of-pearl sheet 4, of the decorative elements 6 not subjected to their stimulus and the color of the color compensation layer 14 deposited in the first empty areas 10 and which appears through the second empty areas 12. The decor elements 6 not subjected to their stimulus, are completely invisible.

When subjected to their stimulus, the color of the decorative elements changes so that they become visible on the obverse of the dial, through the mother-of-pearl sheet, in relation to the color compensation layer, which n is then more effective.

According to another embodiment shown in the figure 2 , the color compensation layer 14 is provided on the obverse of the mother-of-pearl sheet only on the second empty zones 12 opposite the first empty zones 10. As in the previous variant, the mother-of-pearl sheet 4 and the decorative elements 6 are assembled to the support 2 by a layer of adhesive 8.

Thus, thanks to the color compensation layer 14 according to the invention, a user 16 looking at the obverse of the mother-of-pearl sheet 4 does not perceive a difference in color between the color, through the mother-of-pearl sheet 4, decor elements 6 not subjected to their stimulus and the color of the color compensation layer 14 deposited on the second empty areas 12. The decor elements 6 not subjected to their stimulus, are completely invisible.

When subjected to their stimulus, the color of the decorative elements changes so that they become visible on the obverse of the dial, through the mother-of-pearl sheet, in relation to the color compensation layer, which n is then more effective.

According to another embodiment shown in the figure 3 , the reverse of the mother-of-pearl sheet 4 comprises blind cavities 16 filled with reactive lacquer to form the decorative elements 6.

In this embodiment, the color compensation layer 14 according to the invention is provided on the reverse of the mother-of-pearl sheet 4 only on the first empty areas 10 around the decor elements 6, as for the embodiment of the figure 1 .

According to another variant of the invention, the obverse of the mother-of-pearl sheet 4 may also include a diffusive surface 18 over the entire surface or only on the surface of the second empty zones 12 opposite the first empty zones 10 occupied by the color compensation layer 14 or only on the surface facing the decor elements 6.

Thus, thanks to the color compensation layer, the invisible nature of the decoration on the obverse of the coin, when it is not under the effect of its stimulus, is improved. It is then possible to use a setting of greater light intensity when it is under the effect of its stimulus, or several decorations giving different light intensities, some of which may be high, without risk of seeing them appear on the obverse of the coin when the stimulus is not applied.

Claims (14)

Dial (1) comprising a support (2), a mother-of-pearl sheet (4) having an obverse and a cuff and covering at least partially the support (2), and at least one decorative element (6) provided on the reverse side of said mother-of-pearl sheet (4), said decorative element (6) being arranged to be visible on the obverse of the mother-of-pearl sheet (4) under the effect of a stimulus and invisible on the obverse of the sheet of mother-of-pearl (4) in the absence of said stimulus, said decorative element (6) defining around it, on the reverse of the mother-of-pearl sheet (4), at least a first empty zone (10), and at least a second empty area (12) on the obverse of the mother-of-pearl sheet (4), facing said first empty area (10), characterized in that said dial (1) comprises at least one color compensation layer (14) deposited on at least one of the first empty zone (10) and second empty zone (12), the color of said color compensation layer (14) being chosen so that the color difference ΔE da ns the CIE Lab color space between the color compensation layer and the decoration element in the absence of said stimulus, perceived by a user looking at the obverse of the mother-of-pearl sheet, is less than 3, preferably less than or equal to 1. Dial according to claim 1, characterized in that the color compensation layer is provided on the reverse of the mother-of-pearl sheet only on the first empty area around the decorative element. Dial according to claim 1, characterized in that the color compensation layer is provided over the entire surface of the reverse of the mother-of-pearl sheet. Dial according to one of the preceding claims, characterized in that the color compensation layer is provided on the obverse of the mother-of-pearl sheet only on the second empty zone. Dial according to one of claims 1 to 3, characterized in that the color compensation layer is provided over the entire surface of the obverse of the mother-of-pearl sheet. Dial according to one of the preceding claims, characterized in that the color compensation layer is organic or inorganic in nature, or a combination of both. Dial according to claim 6, characterized in that the color compensation layer deposited on the first empty area is metallic. Dial according to one of the preceding claims, characterized in that the surface of at least one of the first and second empty zones is diffusive, said at least one of the surfaces being arranged on the obverse or on the reverse Dial according to one of the preceding claims, characterized in that the reverse of the mother-of-pearl sheet comprises at least one blind cavity receiving the decorative element. Dial according to claim 9, characterized in that the reverse of the mother-of-pearl sheet comprises several blind cavities of different depth in order to receive several decorative elements which, under the effect of the stimulus, appear with different intensities. Dial according to one of claims 1 to 8, characterized in that the decorative element is arranged on the support. Dial according to claim 11, characterized in that it comprises a corresponding engraving on the reverse. Dial according to one of the preceding claims, characterized in that the decorative element comprises phosphorescent or photochromic particles to be sensitive to a light stimulus, electromromic particles to be sensitive to an electrical stimulus, or thermochromic particles to be sensitive to a change in temperature. Timepiece comprising a dial according to one of claims 1 to 12.

Images